1. Field of the Invention
The present invention relates in general to water rides, and specifically a method and apparatus for providing a flowing body of water on a containerless surface with a portion thereof being inclined. By regulating the speed and depth of flow in relation to the area and angles of containerless incline, novel flow dynamics are generated which enable rider controlled water-skimming activity analogous to the sport of surfing.
2. Description of the Related Art
For the past 25 years, surfboard riding and associated wave riding activities, e.g., knee-boarding, body or xe2x80x9cBoogiexe2x80x9d boarding, skim-boarding, surf-kayaking, inflatable riding, and body surfing (all hereinafter collectively referred to as wave-riding) have continued to grow in popularity along the world""s surf endowed coastal shorelines. In concurrence, the 80""s decade has witnessed phenomenal growth in the participatory family water recreation facility, i.e., the waterpark. Large pools with manufactured waves have been an integral component in such waterparks. Several classes of wavepools have successfully evolved. The most popular class is that which enables swimmers or inner-tube/inflatable mat riders to bob and float on the undulating unbroken swells generated by the wave apparatus. Although small breaking waves can result from this class of wavepool, it is not an ideal wave for wave-riding. A few pools exist that provide large turbulent white-water bores that surge from deep to shallow pool end. Such pools enable white water bore (broken wave) riding, however, broken wave riding is not preferred by the cognoscenti of the wave-riding world. The type wave which holds ultimate appeal to a wave-rider is a combination of unbroken yet rideable wave face with a xe2x80x9cbreakingxe2x80x9d/xe2x80x9ctransitioningxe2x80x9d curl or spill.
The ideal unbroken yet rideable wave face can be described as a smooth inclined mound of water of at least one meter in height with a face of sufficient incline such that the gravity force component can allow a rider to overcome the forces of drag and perform water skimming (e.g., surfing) maneuvers thereon. The classic breaking wave can be described as one moving obliquely incident to a beach; having a wave height in excess of one meter; having a portion closest to the beach that is broken, while that portion farthest from the beach has a smooth surface; having the transition from the smooth to the broken part of the wave occurring continuously over a region spanning a few wave heights; and having a transition area with a duration in excess of 10 seconds. In a breaking wave, this transition area is of particular interest to the wave-rider. The transition area is where the wave-rider performs optimum water skimming (e.g., surfing) maneuvers. The transition area is also where the wave face reaches its maximum angle of steepness.
As a wave-rider develops in skill from beginner to advanced, he or she will seek mastery upon different types of waves. First timers start on the xe2x80x9cinsidexe2x80x9d with an already broken white water bore. These waves are the easiest to catch, however, they offer little opportunity for surfing maneuvers. The next step is to move to the xe2x80x9coutside, Just past the break zone. Here a beginner prefers an unbroken wave with only enough steepness to allow them to xe2x80x9ccatchxe2x80x9d the wave. As the wave breaks, beginners prefer a gentle spilling type wave. The more advanced a wave-rider becomes the greater is the preference for steeper waves, with an ultimate wave shape resembling a progressive tube or tunnel.
For years, inventors have attempted to mechanically duplicate the ideal wave for wave-riding that will offer the complete range of wave-riding experience for beginners and advanced riders alike. The majority of such attempts focus on reproduction of travelling, progressive gravity waves found naturally occurring at a beach. Unfortunately, such attempts have met with limited success for wave-riding. Problems inherent to travelling progressive wave technology include: safety, skill, cost, size and capacity. Reproduction of travelling, progressive breaking waves require a large pool with expensive wave generating equipment. Desired increases in wave size result in inherently more dangerous conditions, e.g., deeper water and strong currents. Access to travelling progressive waves usually requires a strenuous swim or paddle through broken waves in order to properly position oneself in the unbroken wave xe2x80x9ctake-off zone.xe2x80x9d Catching a progressive breaking wave requires split-second timing and developed musculature. Riding a progressive breaking wave requires extensive skill in balancing the hydrodynamic lift forces associated with a planing body and the buoyancy forces associated with a displacement body. Progressive waves are an inherently low capacity attraction for water parks, i.e., one or two riders per wave. As a consequence of limited wave quality, inordinate participant skill, excessive cost, potential liability, and large surface area to low rider capacity ratios, wavepools specifically designed to produce conventional travelling progressive breaking waves have proven, with few exceptions, unjustifiable in commercial application.
Le Mehaute (U.S. Pat. No. 3,802,697) and the following three publications: (1) Hornung, H G and Killen, P., xe2x80x9cA Stationary Oblique Breaking Wave For Laboratory Testing Of Surfboards,xe2x80x9d Journal of Fluid Mechanics (1976), Vol 78, Part. 3, pages 459-484; (2) P. D. Killen, xe2x80x9cModel Studies Of A Wave Riding Facility,xe2x80x9d 7th Australasian Hydraulics and Fluid Mechanics Conference, Brisbane, (1980); and (3) P. D. Killen and R. J. Stalker, xe2x80x9cA Facility For Wave Riding Research,xe2x80x9d Eighth Australasian Fluid Mechanics Conference, University of Newcastle, N.S.W. (1983), (all three articles will be collectively referred to as xe2x80x9cKillenxe2x80x9d) describe the production of a unique class of progressive waves called a stationary wave. Stationary waves, as opposed to the aforementioned travelling waves, are normally found in rivers where submerged boulders act to disturb the flowing river water, creating a wave which advances against the current at an equal and opposite speed to remain stationary relative to the bottom.
The stationary breaking waves as contemplated by Le Mehaute and Killen avoid the xe2x80x9cmoving targetxe2x80x9d problem associated with travelling progressive gravity waves. Consequently, from a shore bound observer""s perspective, they are more predictable, easier to observe, and easier to access. Although improved, the stationary breaking waves of Le Mehaute and Killen when applied to the commercial water recreation setting are still plagued by significant progressive wave problems. In particular these problems include: inordinate rider skill to catch and ride the wave, deep water drowning potential (since the water depth is greater than the height of the breaking wave) and high costs associated with powering the requisite flow of water to form the wave. In other words, both Le Mehaute and Killen still contemplate relatively deep bodies of water comparable to that found at the ocean shore.
Furthermore, the wave forming process of Le Mehaute and Killen involves an obstacle placed in a flow of water bounded by containment walls. The hydraulic state of the flow is described as supercritical flow going up the face of the obstacle, critical flow at the top or crest of the obstacle as the wave breaks (a towering xe2x80x9chydraulic jumpxe2x80x9d), and subcritical flow over the back of the obstacle. A submerged dividing stream surface splits the supercritical upstream portion from the subcritical downstream portion which flows over the back of their respective obstacles. A corollary to this xe2x80x9ccritical flowxe2x80x9d breaking process (i.e., where the Froude number equals one at the point of break) is the relationship of water depth with wave size, wherein the maximum wave height obtainable is ⅘ the water depth. Consequently, in Killen and Le Mehaute, the larger the desired wave the deeper the associated flow.
The above-described disadvantage has enormous economic significance. Killen and Le Mehaute require pumps with enormous pumping capacity to produce a larger sized wave. Furthermore, a rider""s performance under a deep flow condition requires great skill. By way of example, when a waverider paddles to catch a wave in a deep water flow (a deep water flow is where the pressure disturbance due to the rider and his vehicle is not influenced by the proximity of the bottom) his vehicle serves primarily as a displacement hull sustained by the buoyancy force and transitions to primarily a planing hull (reducing the draft of the board) as a result of the hydrodynamic lift that occurs from paddling and upon riding the wave. The forces involved in riding this wave is a combination of buoyancy and hydrodynamic lift. The faster the board goes the more the lift is supporting the weight of the rider and the less the buoyancy force. In reaction to this lift, there is an increase in pressure directly underneath the board. This pressure disturbance diminishes at a distance from the board in ratio to one over the square of the distance.
In a deep water flow environment, by the time the pressure disturbance reaches the flow bed, it has already attenuated to such a low level that the bottom creates a negligible influence on that pressure disturbance. Consequently, there is no reaction to be transferred to the rider. This lack of bottom reaction in a deep water flow leaves a rider with no support. Lack of support results in greater physical strength required to paddle, and to transition the surfboard from a displacement hull to a planing hull, in order to catch the wave. Lack of support also results in greater instabilities with axiomatic greater skill required to ride the wave. Furthermore, a deep water flow has inherently increased drowning potential. For example, a 2 foot high breaking wave requires a 5.38 knot current in 2.5 feet of water. Not even an Olympic swimmer could avoid being swept away in such current.
Frenzl (U.S. Pat. Nos. 3,598,402 (1971), 4,564,190 (1986) and 4,905,987 (1990)) describes water flow up an incline. However, in addition to the above-described disadvantages, the structure of Frenzl is described as the bottom of a container. The side walls of this container function to constrain the water flow in its upward trajectory in expectation of conserving maximum potential energy for subsequent recirculation efficiency. However, it has been found that such side walls propagate oblique waves which can interfere with the formation of supercritical flow and eliminate the possibility of breaking waves. That is, the container of Frenzl simply fills with water and submerges any supercritical flow. The side wall containment also proves detrimental in its ability to facilitate ride access. Further, Frenzl""s device is designed for wave riding in equilibrium. The majority of wave riding maneuvers, however, require movement or oscillation around a point of equilibrium through the various zones of inequilibrium, in order to achieve maneuvers of interest.
Accordingly, it is a principle object and advantage of the present invention to overcome some or all of these limitations and to provide an improved stationary wave forming apparatus and method which eliminates boundary layer induced subcritical flow and associated flow disturbance which greatly diminish wave quality. That is, during the operation of a wave making apparatus having side wall containment, drag forces along the side walls result in localized subcritical flow. The transition from supercritical to subcritical flow along these sidewalls generates an undesirable wave envelope properly termed an xe2x80x9coblique wave.xe2x80x9d
In an inclined flow environment, it is extremely easy for such oblique waves to form, because, as these waves propagate against the flow, they have a downhill component that gains an extra increase in energy from the downhill change in elevation. Since this gain in energy results in a gain in amplitude as the oblique waves move downhill against the current, they create a xe2x80x9cchopxe2x80x9d which not only impairs a rider in his performance of water skimming maneuvers, but also propagates and leads to choking of the entire flow.
Therefore, in order to eliminate these disadvantages, the present invention provides a containerless incline which prevents the formation of oblique waves. The inclined riding surface is configured without lateral water constraints which permit low velocity water runoff, so that the main flow of water up the incline remains at or above desired velocity. Thus, riding wave quality, as well as a diversity of wave types, can be achieved and maintained. It should also be pointed out that, in addition to countless configurations of the present invention, the principals of this invention can be accomplished in accordance with several other methods for eliminating boundary layer induced subcritical flow.
Another feature of the present invention is that the preferred water flow type over the containerless incline is a relatively thin xe2x80x9csheetxe2x80x9d flow, rather than the relatively deep water utilized in the prior art. A sheet flow is where the water depth is sufficiently shallow such that the pressure disturbance caused by a rider and his vehicle is influenced by the riding surface through a reaction force, whose effects on the rider and his vehicle are generally known as the xe2x80x9cground effect.xe2x80x9d This provides for an inherently more stable ride, thus requiring less skill to catch and ride the wave.
In the sheet flow situation, the board is so close to a solid boundary, i.e., the flow bed or riding surface, that the pressure disturbance form the board does not have time to diminish before it comes in contact with the solid boundary. This results in the pressure disturbance transmitting through the fluid and directly to the ground. This allows the ground to participate, as a reaction wall, against the weight of the riders body and helps to support the rider by virtue of the ground effect. Thus, sheet flows are inherently more stable than deeper water flows. From the perspective of an accomplished rider, the ground effect principal offers improved performance in the form of more responsive turns, increased speed, and tighter radius maneuvers resulting from lift augmentation that enables a decrease in vehicle planing area.
Sheet flows also can provide a conforming flow in the sense that the flow generally follows the contours of the riding surface. Therefore, this enables one to better control the shaping of the waves as they conform to the riding surface, while still achieving wave special effects when insufficient velocity at the boundary layer allows for flow separation from the contoured flow bed.
In this regard, it should be pointed out that, with a sheet flow up a containerless incline, no wave is necessarily required in order for a rider to enjoy a water attraction constructed in accordance with the principals of the present invention. All that is required is an incline of sufficient angle to allow the rider to slide down the upwardly sheeting flow. Furthermore, intentional rider-induced drag can slow the rider and send him back up the incline to permit additional maneuvers. Likewise, if desired, the rider can achieve equilibrium (e.g., a stationary position with respect to the flow) by regulating his drag relative to the uphill waterflow.
Another feature of the present invention is that, whenever a hydraulic jump occurs, there is no critical and subcritical flow over the top and back of the obstacle (i.e., xe2x80x9ccontainerless inclinexe2x80x9d), in fact, the top or crest of the obstacle utilized by the subject invention is dry. Additionally, the subject invention describes a separation streamline that not only defines the transition from supercritical to subcritical, it divides the wet lower portion of the incline surface from its dry upper portion. The phenomenon of a separation streamline is absent in the prior art. Of great significance is the fact that the subject invention has no correspondence between wave size and water depth; consequently, the illusion of a large wave can be produced with advantageous shallow flows.
The principals of the present invention are applicable to incredibly diverse stationary wave conditions. For example, the degree of inclination of the inclined riding surface can be varied widely to achieve various effects. The riding surface can also be canted about its longitudinal axis or provided with mounds, shapes, forms, or a variety of contours to produce a wave of a particular shape.
The riding surface can also be extended, shortened, symmetrical, asymmetrical, planar, or have a complex curvature. In addition, the depth or velocity of the flow can be varied from one ride to another, or even in a gradient on a single ride. Also, of course, all of the above parameters can be varied individually or simultaneously, along with other parameters within the scope of this invention.
To better understand the advantages of the invention, as described herein, a more detailed explanation of a few terms set forth below is provided. However, it should be pointed out that these explanations are in addition to the ordinary meaning of such terms, and are not intended to be limiting with respect thereto.
Deep water flow is a flow having sufficient depth such that the pressure disturbance from the rider and his vehicle are not significantly influenced by the presence of the bottom.
A body of water is a volume of water wherein the flow of water comprising that body is constantly changing, and with a shape thereof at least of a length, breadth and depth sufficient to permit water skimming maneuvers thereon as limited or expanded by the respective type of flow, i.e., deep water or sheet flow.
Water skimming maneuvers are those maneuvers capable of performance on a flowing body of water upon a containerless incline including: riding across the face of the surface of water; riding horizontally or at an angle with the flow of water; riding down a flow of water upon an inclined surface countercurrent to the flow moving up said incline; manipulating the planing body to cut into the surface of water so as to carve an upwardly arcing turn; riding back up along the face of the inclined surface of the body of water and cutting-back so as to return down and across the face of the body of water and the like, e.g., lip bashing, floaters, inverts, aerials, 360""s, etc. Water skimming maneuvers can be performed with the human body or upon or with the aid of a riding or planing vehicle such as a surfboard, bodyboard, water ski(s), inflatable, mat, innertube, kayak, jet-ski, sail boards, etc. In order to perform water skimming maneuvers, the forward force component required to maintain a rider (including any skimming device that he may be riding) in a stable riding position and overcome fluid drag is due to the downslope component of the gravity force created by the constraint of the solid flow forming surface balanced primarily by momentum transfer from the high velocity upward shooting water flow upon said forming surface. A rider""s motion upslope (in excess of the kinetic energy added by rider or vehicle) consists of the rider""s drag force relative to the upward shooting water flow exceeding the downslope component of gravity. Non-equilibrium riding maneuvers such as turns, cross-slope motion and oscillating between different elevations on the xe2x80x9cwavexe2x80x9d surface are made possible by the interaction between the respective forces as described above and the use of the rider""s kinetic energy.
The equilibrium zone is that portion of a inclined riding surface upon which a rider is in equilibrium on an upwardly inclined body of water that flows thereover; consequently, the upslope flow of momentum as communicated to the rider and his vehicle through hydrodynamic drag is balanced by the downslope component of gravity associated with the weight of the rider and his vehicle.
The supra-equidyne area is that portion of a riding surface contiguous with but downstream (upslope) of the equilibrium zone wherein the slope of the incline is sufficiently steep to enable a water skimming rider to overcome the drag force associated with the upwardly sheeting water flow and slide downwardly thereupon.
The sub-equidyne area is that portion of a riding surface contiguous with but upstream (downslope) of the equilibrium zone wherein the slope of the incline is insufficiently steep to enable a water skimming rider to overcome the drag force associated with the upwardly sheeting water flow and stay in equilibrium thereon. Due to fluid drag, a rider will eventually move in the direction of flow back up the incline.
The Froude number is a mathematical expression that describes the ratio of the velocity of the flow to the phase speed of the longest possible waves that can exist in a given depth without being destroyed by breaking. The Froude number equals the flow speed divided by the square root of the product of the acceleration of gravity and the depth of the water. The Froude number squared is a ratio between the kinetic energy of the flow and its potential energy, i.e., the Froude number squared equals the flow speed squared divided by the product of the acceleration of gravity and the water depth.
Subcritical flow can be generally described as a slow/thick water flow. Specifically, subcritical flows have a Froude number that is less than 1, and the kinetic energy of the flow is less than its gravitational potential energy. If a stationary wave is in a sub-critical flow, then, it will be a non-breaking stationary wave. In formula notation, a flow is subcritical when v less than square root gd where v=flow velocity in ft/sec, g=acceleration due to gravity ft/sec2, d=depth (in feet) of the sheeting body of water.
Critical flow is evidenced by wave breaking. Critical flow is where the flow""s kinetic energy and gravitational potential energy are equal. Critical flow has the characteristic physical feature of the hydraulic jump itself. Because of the unstable nature of wave breaking, critical flow is difficult to maintain in an absolutely stationary state in a moving stream of water given that the speed of the wave must match the velocity of the stream to remain stationary. This is a delicate balancing act. There is a match for these exact conditions at only one point for one particular flow speed and depth. Critical flows have a Froude number equal to one. In formula notation, a flow is critical when v=square root gd where v=flow velocity, g=acceleration due to gravity ft/sec2, d=depth of the sheeting body of water.
Supercritical flow can be generally described as a thin/fast flow. Specifically, supercritical flows have a Froude number greater than 1, and the kinetic energy of the flow is greater than its gravitational potential energy. No stationary waves are involved. The reason for the lack of waves is that neither breaking nor non-breaking waves can keep up with the flow speed because the maximum possible speed for any wave is the square root of the product of the acceleration of gravity times the water depth. Consequently, any waves which might form are quickly swept downstream. In formula notation, a flow is supercritical when v greater than square root gd where v=flow velocity in ft/sec, g=acceleration due to gravity ft/sec2, d=depth (in feet) of the sheeting body of water.
The hydraulic jump is the point of wave-breaking of the fastest waves that can exist at a given depth of water. The hydraulic jump itself is actually the break point of that wave. The breaking phenomenon results from a local convergence of energy. Any waves that appear upstream of the hydraulic jump in the supercritical area are unable to keep up with the flow, consequently they bleed downstream until they meet the area where the hydraulic jump occurs; now the flow is suddenly thicker and now the waves can suddenly travel faster. Concurrently, the down stream waves that can travel faster move upstream and meet at the hydraulic jump. Thus, the convergence of waves at this flux point leads to wave breaking. In terms of energy, the hydraulic jump is an energy transition point where energy of the flow abruptly changes from kinetic to potential. A hydraulic jump occurs when the Froude number is 1.
A stationary wave is a progressive wave that is travelling against the current and has a phase speed that exactly matches the speed of the current, thus, allowing the wave to appear stationary.
A white water occurs due to wave breaking at the leading edge of the hydraulic jump where the flow transitions from critical to sub-critical. In the flow environment, remnant turbulence and air bubbles from wave breaking are merely swept downstream through the sub-critical area, and dissipate within a distance of 7 jump heights behind the hydraulic lump.
Separation is the point of zero wall friction whereas the sheet flow breaks away from the wall of the incline or other form or shape placed thereon. In this regard, a two dimensional riding surface should be distinguished from a three dimensional riding surface. The former is essentially a smooth or uniform planar surface, which may or may not be planar, while the latter has uniform characteristics as well as raised or contoured shapes mounted thereon to produce unique wave features.
Flow separation results from differential losses of kinetic energy through the depth of the sheet flow. As the sheet flow proceeds up the incline it begins to decelerate, trading kinetic energy for gravitational potential energy. The portion of the sheet flow that is directly adjacent to the walls of the incline (the boundary layers) also suffer additional kinetic energy loss to wall friction. These additional friction losses cause the boundary layer to run out of kinetic energy and come to rest in a state of zero wall friction while the outer portion of the sheet flow still has residual kinetic energy left. At this point the outer portion of the sheet flow breaks away from the wall of the incline (separation) and continues on a ballistic trajectory with its remaining energy forming either a spill down or curl over back upon the upcoming flow.
The boundary layer is a region of retarded flow directly adjacent to a wall due to friction.
The separating streamline is the path taken by the outer portion of the sheet flow which does not come to rest under the influence of frictional effects, but breaks away from the wall surface at the point of separation.
Flow partitioning is the lateral division of flows having different hydraulic states.
A dividing streamline is the streamline defining the position of flow partitioning. The surface along which flows divide laterally between super critical and critical hydraulic states.
A bore is a progressive hydraulic jump which can appear stationary in a current when the bore speed is equal and opposite to the current.
A velocity gradient is a change in velocity with distance.
A pressure gradient is a change in pressure with distance.
Conforming flow occurs where the angle of incidence of the entire depth range of a body of water is (at a particular point relative to the inclined flow forming surface over which it flows) predominantly tangential to this surface. Consequently, water which flows upon an inclined surface can conform to gradual changes in inclination, e.g., curves, without causing the flow to separate. As a consequence of flow conformity, the downstream termination of an inclined surface will always physically direct and point the flow in a direction aligned with the downstream termination surface. The change in direction of a conforming flow can exceed 180 degrees.
The subject invention seeks not only to solve the previously identified problems of existing unbroken wave and breaking wave methodologies, it also attempts to pioneer a whole new realm of water ride dynamics, as yet unexplored by current art. In addition to a sheet flow of water upon a containerless upwardly inclined surface, alterations to this combination, through adjustments to water depth, water speed, water direction, surface area, surface shape (contour), and surface altitude, create wave like shapes that simulate: a white water bore; an unbroken yet rideable wave face; a spilling breaking wave; and, a breaking tunnel wave. Alterations can also create a fluid environment with ride performance characteristics superior to those available on naturally occurring progressive waves, e.g., greater lift and speed. Furthermore, functional structural additions to a containerless incline will allow creation of an array of new water ride attractions presently unknown in nature or the water recreation industry.
The reason the subject invention can succeed in its objectives is that it does not duplicate naturally breaking progressive waves, rather, it creates xe2x80x9cflow shapesxe2x80x9d from high velocity sheet flows over a suitably shaped forming surface. The majority of flow manifestations created by the subject invention are technically not waves. They may appear like gravity waves breaking obliquely to a beach; however, these sheet flow manifestations are distinct hydrodynamic phenomena caused by the interaction of four dynamics: (1) the subject invention""s unique surface architecture; (2) the trajectory of the water relative to the flow forming surface; (3) flow separation from this surface; and (4) changes in hydraulic state of the flow (i.e., supercritical, critical or subcritical) upon this surface.
Accordingly, several advantages of the subject invention are:
a) to provide an inclined containerless surface upon which a uniform flow of water can produce a body of water that simulates a kind prized by surfers in the first stage of wave riding, i.e., an unbroken yet rideable wave face. This body of water has the appearance of a stationary wave in a subcritical flow, however, it is actually formed by supercritical water flowing over the containerless surface. Advantages of containerless surface embodiments include: (1) improved start characteristics through side ventilation of transient surge; (2) smooth water flow by avoiding undesirable oblique waves induced by enclosure, e.g., channel walls; (3) safe and rapid rider ingress or egress without channel wall obstruction; (4) elimination of operational downtime associated with containment flooding; (5) elimination of pump and valve equipment as required to remedy a containment flood; (6) elimination of expensive quick open/close valves as required for instantaneous starting of supercritical flow; (7) elimination of complex and expensive control equipment as required to coordinate valve opening/closing and pump on/off operation; and (8) increased ride capacity through a forgiving open flow architecture.
b) to provide an inclined containerless surface upon which a uniform flow of water can produce a body of water that simulates a kind prized by first time wave-riders, i.e., a broken white water bore. The white water bore effect results from supercritical flow moving up the incline transitioning by way of a hydraulic jump across the incline to produce a two dimensional stationary breaking wave that simulates the white water bore in the absence of flow over the back side of the incline. The containerless surface allows the spilling white water to ventilate laterally and avoid supercritical flow submersion.
c) to introduce a cross-stream velocity gradient to a flow of water that moves up a containerless surface with level ridge line, which then produces a body of water that simulates a kind prized by beginning surfers while riding a wave, i.e., a spilling wave with unbroken shoulder. The xe2x80x9cbreaker likexe2x80x9d effect results from the flow having two coexisting hydraulic states, i.e., a higher velocity supercritical flow over the top of ridge line and an adjacent lower velocity supercritical flow that fails to reach the ridge line due to insufficient kinetic energy. This lower energy supercritical flow will decelerate to a critical state and form a hydraulic jump below the ridge line with an associated subcritical spill of turbulent water occurring to the side of the supercritical flow. If the adjacent flow were subcritical, then it would merge with the supercritical flow by means of a streamwise oblique hydraulic jump. The containerless surface allows the spill of turbulent white water to ventilate and avoid complete supercritical flow submersion.
d) to controllably cause a cross-stream velocity gradient to occur and simulate the previously described spilling wave with unbroken shoulder by either a properly designed pump means or nozzle means.
e) to provide an asymmetrically extended containerless surface upon which a uniform flow velocity produces a body of water that simulates a kind prized by beginning wave-riders, i.e., a spilling wave with unbroken shoulder. The asymmetrically extended containerless surface forms a downstream ridge line of increasing elevation. A flowing body of water with kinetic energy sufficient to overflow the low side supercritically, but insufficient energy to overflow the high side will exhibit flow partitioning, i.e., the flow to the high side will transition to subcritical as evidenced by a hydraulic jump and associated white water. A corollary to containerless surface asymmetry is its ability to solve the transient surge problems associated with ride start-up and rider induced flow decay upon upwardly inclined flow surfaces, i.e., creation of asymmetrically inclined flow forming surface provides a maximum height ridge line of decreasing elevation to facilitate self-clearing of undesirable transitory surges and excess white water.
f) to provide an extended surface comprised of a substantially horizontal flat surface (the sub-equidyne area) that extends the aforementioned containerless inclined surface in the upstream direction. The extended surface facilitates a riders ability to maximize his forward speed by the riders own efforts of xe2x80x9cpump-turning,xe2x80x9d hereinafter more fully described as the acceleration process. The acceleration process permits the rider to gain additional velocity in a manner analogous to how a child on a swing generates additional velocity and elevation. Given that the heart and soul of surfing is to enable a rider to enjoy the feel and power of increased velocity that results from cyclical transition between the supra-equidyne area and sub-equidyne area relative to a position of equilibrium, the extended surface provides a significant advantage. A corollary improvement to the extended surface is to tilt the extended surface in a direction perpendicular to its extension to provide a gravity induced sideways component that causes a rider to move in the direction of fall. Such motion has the added benefit of increased throughput capacity by hastening a riders course through the apparatus.
g) to provide a three dimensional contoured containerless surface from flat to incline that produces a body of water that simulates a kind prized by intermediate to expert wave-riders, i.e., an unbroken yet rideable shoulder with tunnel wave of variable size dependent upon flow velocity. That is, the essentially two dimensional riding surface may be provided with a contoured shape or form to create a three dimensional flow bed which produces unique wave features. The tunnel portion of this body of water has a mouth and an enclosed tunnel extending for some distance into the interior of the forward face of the wave-shape within which the wave rider seeks to ride. This tunnel portion has the appearance of a plunging progressive wave as found on natural beaches. However, it actually results from contour induced supercritical flow separation. An advantage of flow separation is the ability of a properly shaped containerless incline to generate tunnel waves that grow in size (i.e., tunnel diameter) in relation to an increase in the velocity of water flowing thereover yet without requiring an increase in water depth or change in shape or size of the containerless incline. As this supercritical tunnel reattaches itself at the toe of the incline, the containerless surface allows the turbulent water to ventilate and avoid supercritical flow submersion. Flow separation also allows tunnel wave formation upon a containerless incline forming surface that is not curved back upon itself, and in fact, can be substantially less than vertical. A less than vertical containerless incline flow forming surface is easier to design and construct since it avoids complicated coordinate mapping and structural support problems. Additionally, this containerless surface arrangement allows tunnel wave formation in both deep water and sheet flow conditions.
h) to provide a beyond vertical extension of a three dimensional contoured containerless surface that produces a conformed body of water that simulates a kind prized by intermediate to expert wave-riders, i.e., a tunnel wave with unbroken yet rideable shoulder. As distinguished from the tunnel wave as described in (f) supra, a beyond vertical extension allows high velocity flow tunnel formation without separation. This containerless surface arrangement advantageously allows tunnel wave formation in situations where flow velocity head is significantly higher than the vertical height of the wave forming means.
i) to provide a flow of water upon the previously described contoured containerless surfaces that (by way of a progressive increase of flow velocity) transforms this flow from a simulated stationary white water bore along the entire forming means, to a simulated spilling wave with unbroken shoulder, to the final tunnel wave with unbroken yet rideable shoulder. This method is hereinafter referred to as the xe2x80x9cwave transformation process.xe2x80x9d The wave transformation process has the advantage of enabling a rider to enjoy or an operator to provide a multiplicity of wave types, e.g., white water bore, unbroken, spilling or tunnel, upon a single properly configured appliance all within a relatively short time span.
j) to provide longitudinal movement across an inclined containerless surface of a sufficiently sized upwardly sheeting body of water (hereinafter referred to as a xe2x80x9cswathxe2x80x9d) to permit a rider(s) to match his longitudinal speed with the speed of the swath and perform water skimming maneuvers thereon. This moving swath will provide the practical benefit of increasing rider throughput capacity and reducing the overall energy requirements of flow across the entire inclined containerless surface. This embodiment will also provide a rider or operator with the added benefit of participant movement to an end point that is different from the beginning point. Furthermore, by altering the contour of the containerless surface or the direction or speed of flow, differing wave conditions (e.g, spilling, tubing, etc.) can be produced during the course of the ride.
k) to provide a source of flow that is free of oblique waves. In this regard, in one embodiment of the subject invention positions the point of flow source, e.g., aperture, nozzle or weir at one elevation which is connected to a declining surface, which transitions to a horizontal surface, which then transitions to an inclined surface.
l) to provide an apparatus that will enable riders to perform water skimming maneuvers in a format heretofore unavailable except by analogy to participants in the separate and distinct sports of skateboarding and snowboarding, to wit, half-pipe riding. In this regard, the present invention provides a containerless surface for forming a body of water with a stable shape and an inclined surface thereon substantially in the configuration of a longitudinally oriented half-pipe. Such form is hereinafter referred to as the xe2x80x9cfluid half-pipe.xe2x80x9d A corollary improvement to the fluid half-pipe is to provide an apparatus that permits an increased throughput capacity by increasing the depth of the fluid half-pipe in the direction of its length. This increase in depth will have the added benefit of causing a rider to move in the direction of fall and facilitate his course through the ride.
m) to provide a pliable containerless surface capable of distortion or peristaltic movement by an auxiliary motion generating device. Containerless surface distortion will alter flow pressure gradients thus manifesting stationary yet changeable wave characteristics, e.g., spilling waves, tunnel waves, or even differing types of tunnel waves. Sequential undulation or peristaltic movement of a pliable containerless surface will provide a novel traveling wave with varying wave characteristics. Such device has the added benefit of participant movement to an end point that is different from the beginning point with increased rider throughput capacity.
n) to provide a flow of water for all containerless surfaces as described above in either a deep water or sheet flow format. Deep water flows upon containerless surfaces will simulate ocean like surfing conditions and enable a controlled venue for instruction, contests, or general recreation. Sheet flows upon containerless surfaces will increase safety due to reduced water depth; reduced water maintenance due to decrease in volume of water treated; reduced energy costs by minimizing the amount of pumped water; reduce the requisite skill level of participants as the result of easy ride access and improved ride stability due to xe2x80x9cground effectsxe2x80x9d; and improved ride performance (i.e., lift and speed) due to ground effects.
o) to utilize a uniquely distinct wave forming process, i.e., flow separation, that creates the illusion of a large deep water wave through utilization of advantageous shallow flows.
p) to connect an inclined containerless surface to other attractions, e.g., a xe2x80x9clazy river,xe2x80x9d xe2x80x9cvortex pool, conventional white water rapid ride, conventional wave pool,xe2x80x9d or xe2x80x9cactivity pool.xe2x80x9d Such connection would enable a rider to enjoy in unique combination other successful attractions known to those skilled in the art. Such combination has the significant advantage of added rider capacity and utilization of the kinetic energy of motion of water that exits from the inclined containerless surface, thus serving in a co-generative capacity, e.g., powering riders around the length of a connected xe2x80x9clazy river.xe2x80x9d
q) to provide a fence that permits ventilation of spilled white water, avoids oblique wave formation, and allows control of rider ingress or egress from all sides of a containerless incline. Such fence could also be used to serve as a dividing mechanism to create lanes to prohibit rider contact and promote safety.
r) to provide a riding vehicle connected to a containerless surface and positioned to hydroplane within the flow. A moveable tether can serve as a conveyance mechanism from a starting position outside the flow to a planing position in the flow. Thereupon, the tether can either continue to serve in a conveyance fashion to controllably transport a rider to the ride terminus outside the flow, or, the tether can be released to allow the rider to control his own destiny. A moveable tether will provide the practical benefit of facilitating rider entry and increasing rider throughput capacity.
s) to provide a slide entry mechanism that safely and rapidly introduces participants into an inclined containerless surface flow.
t) to incorporate a containerless inclined surface with a dam or reservoir as a method for dispersing excessive potential energy of a higher elevation body of water flowing to a lower elevation. Such method could be advantageously used to safely control spill-off and prevent downstream erosion.
For purposes of summarizing the invention and the advantages achieved over the prior art, certain objects and advantages of the invention have been described herein above. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.
All of these embodiments are intended to be within the scope of the invention herein disclosed. These and other embodiments of the present invention will become readily apparent to those skilled in the art from the following detailed description of the preferred embodiments having reference to the attached figures, the invention not being limited to any particular preferred embodiment(s) disclosed.